Steel tower or derrick.



L. C. RIORE.

STEEL TOWER 0R DERIIICK.

APPLICATION FILED MAY 7. 1913..

Aug. 31, w15.

misi@- vention.

LEE C. MOORE, OF PITTSBURGH, PENNSYLVANIA.

STEEL TOWER 0R BEREICH.

Maisto,

Specification of Letters Patent.

Patented Ang., 31, 119115.

Application led May 7, 1913. Serial No. 766,086.

T0 all whom it may concern Be it known that l, `LEE C. MOORE, a resident^of Pittsburgh, inthe county of Allegheny and State of Pennsylvania, have invented a new and useful lmprovementin Steel Towers or Derricks, of which the fol lowing is a specification.

This invention relates to metal towers, and more especially to oil or gas Well derricks.

The object of the invention is to provide an improved metal tower or derrick which is considerably stronger than prior constructions of this type, and which can be manufactured at less cost and is less liable to collapse than prior similar constructions. A further objectof the invention is to provide a metal tower-or derrick having leg sections'formed of a plurality of tubes, arranged concentrically or one within another, thereby greatly increasing the strength of the leg sections, and enabling the same to be manufactured at a loWv cost.

The invention comprises the construction and arrangement of parts hereinafter described and claimed.

In the accompanying derrick embodying one form of the inven tion; Fig. 2 is a detail sectional elevation, showing'the abutting 'ends of two leg sections and a clamp embracing the same; Fig. 3 is a cross sectional view on the line 3-3, Fig. 2; Fig. l is a longitudinal sectional view on a reduced scale through one of the leg sections shown in Fig. 2; and Fig. 5 is a similar view of another form of the in- The tower or derrick illustrated is of the same general design and arrangement as those illustrated in the' prior Patents, No. 933,386, granted September 7, 1909, to rlhonias A. Neill, and No. 1,015,821, granted January 30, 1912,-to me. lt comprises a plurality of legs 1, of which there may be three, four, or more as desired. These legs are placed on an incline, as is usual, so that the derrick tapers toward the top. rllhe legs are each composed of a series of sections 2, arranged with their ends abutting each other and connected by'clamps or sockets 3. rllhe clamps or sockets 3 may be of any suitable type, such as that shown in my prior ap 1ication, Serial No. 720,882, filed Septem er As illustrated, the clamps consist of sleeves et, formed of resilient, rolled or .cated one within the other.

forged metal slotted or openflongitudinally along one side, as at 5, andtransversely, as at 6, to provide a plurality of radial flanges or ears 6a, 6b. rllhe cylindrical portion of the sleevelembraces the abutting ends of a pair of leg sections 2 throughout more than half the circumference thereof, and the ears 6a extend out radially with respect to the leg-sections at angles of degrees, 90 degrees, or the like, to eachother, in accordance with the number of legs in the particular tower or derrick. The ears 6* lie in parallelism with each other. rThe several legs are connected by horizontal members or girts 7 and diagonal braces 8, the ends of which are bolted or otherwise secured to the Hanges 6a of the clamps or sockets 4. The clamps or sockets 4 are clamped securely around the leg sections by suitable securing bolts 9,

passing `through ears 6b. The structure described to this point is of a common type, such as can be purchased in the open market today. ln the construction of such a .tower or derrick it is necessary to use tubes for the leg sectlons whlchhave been carefully tested to assure that no flaws drawings, Figure 1 is an elevation of a portion of an oil well-,V

exist therein. Usually butt or lap-welded tubesare used, and these are subjected to a yhydraulic pressure test to disclose the pres- EBS ence of any iaws in the tubes. This is necessary in orderto secure the proper factor of safety, as the strength of the tubular leg sections depends to a largeextent upon thecontinuity of the tubular cross section, and any break or Haw in the weld weakens the tube at that point to such an extent that it will either bulge outwardly under the heavy compression, or bend under the lateral bending strain produced by wind or the like. Perfect welded tubes, that is, tubes which have been subjected to 'a pressure test and pronounced free from flaws, are comparatively expensive, much moreso, in fact, than ought to be necessary for the production of a structure of this kind, in which the mechanical .strength of the tube, and not its freedom from leaks or cracks, is the desirable feature.

According to my invention l form each of the several leg sections of a plurality of lll@ used. ln the present tower or derrick the leg sections are each formed of a plurality of concentrically arranged tubes. The leg section shown consists of an outer tube 10, indicated in Fig. 4, which may be of the same external diameter as the tubes commonly employed heretofore, say about three inches, or of any other size, depending upon the size of the derrick and the particular use for which it is designed. Said tubes, however, will be of slightly thinner gage than heretofore, weighing only about seven pounds per foot length. Within the outer tube lO is located inner tubes 11, which in the present embodiment is about two and one-half inches in external diameter, weighing about five pounds per linear foot, and which is a loose or easy fit in the outer tube. After the inner tube is introduced into the outer tube a suitable expanding tool is thrust into the inner tube, and it is then expanded outwardly at one or more points, as at 12, so as to secure a tight fit between the two tubes, making them act practically as a unit. In the form shown in Fig. 4, the tube is expanded outwardly at three points, at its ends and in the middle, although it may be expanded elsewhere and at as many places as desired.

'The leg sections, formed as described and in the manner indicated in Fig. 4, are used in the ordinary way, that'is, they are placed end to end or in abutting relation and secured together by means of the clamps or sockets 4, as shown in Fig. 1. They have the advantage, however, that a lower grade of tube can be used than according to prior practice. The inner tubes in the concrete example referred to weigh about live pounds per linear foot, and the outer tubes about seven pounds per foot, making an increase in weight of only about two pounds per foot over the higher grade tubes used for prior towers or derricks. This increase in the weight of the tubes results in an increase of about 20% in strength. Moreover, the total cross sectional area of the metal in the two tubes is greater than that of the single tube, thus decreasing the liability of two leg sections telescoping each other when they are not of exactly the same size or gage. In addition, there is a decrease in cost of 25%, due to the lower quality of tubes that can of the outer tubes are reinforced, since it is at Athis point that failure most often occurs. Such an arrangement is shown in Fig. 5, where the outer tube l0 is reinforced with an inner tube 11a of only half length, with its end portions expanded outwardly at 12, so that the tubes act as a single unit.

It is of course to be understood that the invention is not limited to the particular sizes of tubes and derricks referred to above, but includes any and all sizes and designs thereof so long as they come within the scope of the claims appended hereto.

What l claim is 1. A leg section for towers, derricks and the like, comprising two tubes concentrically disposed about a common axis and also symmetrically disposed with reference to a plane normal to said axis .midway between the ends of the outer tube, the outer diameter of the inner tube being less than the inner diameter of the outer tube, and the inner tube at intervals along its length having portions of its wall expanded outwardly into close contact with the wall of the outer tube to secure said tubes to each other.

2. A leg section for towers, derricks and the like, comprising two'tubes concentrically disposed about Va com mon axis, the inner tube being shorter than the outer tube and being symmetrically disposed with reference to. a plane normal to said axis midway between the ends of the outer tube, the outer diameter of the inner tube being less than the inner diameter of the outer tube, and the nner tube at intervals along its length having portions of its wall expanded outwardly into close contact with the wall of the outer tube to secure said tubes to each other.

In testimony whereof, l have hereunto set my hand.

LEE C. MOORE.

Witnesses:

ELBERT L. HYDE, WLLLIAM P. LARKIN. 

